The present invention pertains to the field of integrated circuits. More particularly, the present invention relates to regulating power supplied to an integrated circuit inserted in a socket.
Advances in integrated circuit technology continue to provide faster, more robust, and more densely packed integrated circuits. With each technological advance, power delivery, input/output, and thermal solutions become more problematic. FIG. 1 illustrates part of a computer system having power delivery, input/output, and thermal solutions common in the prior art.
In FIG. 1, system board 110 is a printed circuit board to which various other components are attached. Transformer 123 and capacitors 127 of voltage regulator 120 are soldered to system board 110. Central processing unit (CPU) 130 is coupled to system board 110 through socket 140. Heat sink 150 is thermally coupled to CPU 130.
Socket 140 provides the input/output solution for CPU 130. A number of leads 145 connect the various input/output ports (not shown) on CPU 130 to various buses, control lines, and power lines (not shown) on system board 110. Each lead 145 has associated with it a certain amount of inductance. Inductance is related to the length of the leads and must be below a certain critical inductance level in order for input and output operations to work properly. The critical inductance decreases as the operating frequency of CPU 130 increases. In which case, the maximum allowable length of leads 145 tends to decrease as operating frequency increases.
Voltage regulator 120 provides the power delivery solution for CPU 130. CPUs usually operate at different voltage levels and tolerance levels than are typically provided by most power supplies used in computer systems. For instance, a CPU may operate at 1.2 volts DC with a tolerance of plus or minus 0.01 volts. A power supply may provide 5 volts DC with a tolerance of plus or minus 0.25 volts. Another type of power supply may provide a high frequency AC voltage. In either case, in FIG. 1, voltage regulator 120 receives power from the power supply (not shown), and converts the power to a voltage level and tolerance level required by CPU 130.
CPUs also commonly consume power at a higher rate than most power supplies provide. The amount of power that a CPU consumes depends on clock speed (operating frequency) and transistor density. For each clock period, hundreds of thousand, if not millions, of transistors draw current simultaneously. The current is drawn in bursts corresponding to the clock periods. The change in current with respect to time (i.e. the slew rate) for each clock period is likely to be faster than a typical power supply can handle. In which case, in FIG. 1, voltage regulator 120 not only converts power to appropriate voltage and tolerance levels, but also supplies power at the required slew rate. Capacitors 127 store power from the power supply so that it can be provided at the faster slew rate. The amount of capacitance needed to sustain the slew rate for CPU 130 increases as the slew rate increases and increases as the distance between capacitors 127 and CPU 130 increases. Larger capacitance generally means larger and/or more capacitors are needed.
Heat sink 150 provides the thermal solution for CPU 130. Heat sink 150 is situated in close proximity to CPU 130 so that the heat sink can absorb and dissipate the heat generated by the CPU. If the operating speed and/or transistor density of CPU 130 is increased, CPU 130 will generate more heat. The more heat that CPU 130 generates, the more surface area heat sink 150 needs to dissipate heat (assuming all other factors are equal).
Putting the input/output, power, and thermal solutions together causes a variety of design conflicts. Voltage regulator 120 needs to be as close as possible to CPU 130 to provide power at the required slew rate in an efficient manner. Heat sink 150 must also be close to CPU 150 and also requires a certain surface area to absorb and dissipate the CPU""s heat. As shown in the illustrated embodiment, the size of heat sink 150 limits how close voltage regulator 120 can be to the CPU. If socket 140 were taller, voltage regulator 120 could fit under the heat sink and get closer to CPU 130. But, the height of socket 140 is limited by the critical inductance of leads 145 and the need for heat sink 150 to be in contact with CPU 130.
As technology allows CPU 130 to run faster and include more transistors, the design conflicts among the three solutions get worse. The components of voltage regulator 120 get larger, heat sink 150 gets larger, and socket 140 gets shorter. In fact, as power requirements increase, voltage regulator 120 generates so much heat that it needs its own thermal solution, adding complexity and cost to the design. For instance, a typical thermal solution for voltage regulator 120 may includes an additional fan (not shown) which occupies valuable space on system board 110 and requires additional power.
A socket attaches to a first component and includes a receptive area to couple a second component to the first component. A low profile voltage regulator is integrated into the socket and proximately disposed adjacent to the receptive area. The low profile voltage regulator converts a first power signal from the first component to a second power signal for the second component. A chassis encloses the socket and the low profile voltage regulator and serves as a base for a heat sink to be attached to the second component.